The nationalist victor in the Quebec elections was preparing for government on Thursday under the shadow of a police investigation into the murder of a man at the party that celebrated her win.

More details were emerging about the background of Richard Henry Bain, the 62-year-old who was due to make his first court appearance in Montreal in connection with the gun attack on Tuesday night.

Chaos broke out at the Metropolis concert hall minutes after Pauline Marois, the leader of the separatist Parti Quebecois, had begun her victory speech. One man died and another was critically injured – both were outside and were shot as the gunman tried to enter the hall. Marois was bundled off stage by her bodyguards.

A vigil was held on Wednesday night outside the hall, in memory of the man who died. The tragedy has diverted attention away from the substance of the result, which put Marois at the head of what will almost certainly be a weak, minority administration.

Marois come to power at the end of a divisive election campaign. But while the PQ fought partly on a platform based on sovereignty for Quebec and the primacy of the French language, the election also took place against the backdrop of ongoing student protests against tuition fee hikes.

Marois said she intends to stick by her campaign promise to reverse the tuition fee rises and abolish Law 78, a hated piece of legislation that places restrictions on the right to protest. Speaking at a press conference in Montreal on Wednesday, she said: “My government will cancel fees rise by decree. Law 78 will therefore no longer be needed. I intend to propose its repeal and I am convinced that the opposition parties will agree. We will then have a summit on higher education.”

Though this is a huge victory for the student movement, it remains to be seen whether she will be able to form a coalition or convince the opposition to respect these promises.

Her PQ party only beat the Liberals by a thin margin of 30,000 votes, with 54 candidates elected out of 125, on 32% of the popular vote. She will form a cabinet and lead a minority government at the National Assembly in the next two weeks, but it will be one of the weakest provincial governments in Canada, dashing her party’s hopes for an independence referendum for Quebec any time soon.

Meanwhile, after a humiliating defeat in his own district, former Liberal party leader Jean Charest announced to Quebec’s parliament that he was resigning from politics. “I will leave my job in the next few days. After 28 years of public life, it is time for me to take another step, turn the page,” he said, his voice choking with emotion.

Charest’s resignation set social media alight with students and supporters of the Quebec “printemps erable” seeing it as the definitive sign that students had won the battle against the tuition fee hike, or at least that they would hold important political leverage after taking down two education ministers and the prime minister.

Jérémie Bédard-Wien, the finance secretary of Classe, the militant student organisation at the forefront of the strike, told the Guardian that the student movement was celebrating three major victories: the cancellation of the tuition hikes, the repeal of Law 78 and the resignation of Charest.

Bédard-Wien said the victory was the result of “a wave of popular mobilisation that happened through the spring”. He expressed confidence that Marois would keep her promises because “the PQ fears further strikes”.

But he said the struggle against tuition hikes was not over. “In the next few months, students will have to face a proposed indexation of tuition fees to the cost of living, a measure which does not take into account the reality of students. This vision runs counter to ours and we can expect further mobilisation, further strikes and further direct action.”

As well as the repeal of measures linked to the tuition fee rises, Marois plans to prevent construction firms convicted of corruption from getting contracts, to expand affordable daycare services for old people, increase the royalties on natural resources, as well as expand the reach of Law 101, the language law that asserts the dominance of French in the province and which deeply disturbs the minority English-speaking community in Quebec. Marois insisted she would “protect” Anglophone residents in Quebec.

At her press conference, Marois expressed sympathy for the family of the man who was killed at her victory rally. But she denied it was linked to the divisiveness of her campaign. “A man is dead for no reason. Madness has struck,” she said. Visibly shaken by the fatal shooting that interrupted her victory speech the night before, Marois said: “Quebec is a non-violent society. A single act of madness cannot erase this fact.”

Marois called it an isolated incident that did not represent the Quebecois people or bear any relation to the tone and style of her campaign. She urged people not to jump to conclusions, and said: “This is a probably the case of someone with grave mental health issues.”

Police said Bain, 62, was from near Mont Tremblant, a small town in the Laurentian mountains about 80 miles north-west of Montreal. It was not clear whether he was an English or French speaker – an important detail after a bitter election campaign fought on cultural and language issues. There are reports that, when he was arrested, he declared: “The Anglophones are waking up.”

Marois said she did not fear for her own security after being taken backstage where she could see a fire and an injured man, but rather worried what would happen if the crowd in the concert hall brimming with enthusiasm suddenly panicked. “I asked my bodyguard to be back on stage because I was afraid for the crowd – we were so many in the meeting. I asked them to go outside slowly.”

The dead man was named as Denis Blanchette, 48, a lighting technician who was smoking in the alleyway outside the hall, waiting for the event to end so he could take down the rig. He was shot as the gunman opened fire outside.

David Courage, 27, a musician, was shot and critically injured. Police dragged him inside the hall to treat him. Witnesses say after the two were shot, the gunman’s weapon jammed and he was tackled by police.